Mindfulness approaches seem particularly useful for people with chronic or relapsing symptoms, such as severe relapsing depression, rather than for first-episode or acute conditions.

For example, a key study published in 2000 found that mindfulness-based CBT had a beneficial effect on people who had three or more relapse of depression, but not people who had experienced two relapses or less.

The idea is quite different from cognitive approaches, where clients are encouraged to identify, evaluate and retrain their problematic thoughts and behaviours.

Mindfulness instead encourages people to be fully aware of these troublesome thoughts or sensations, but not to engage with them.

In other words, clients are encouraged to develop a degree of separation from their thoughts and emotions, so they can experience them, but not feel that they are fully controlled by them.

Some research has suggested that this is because mindfulness (and indeed other approaches) improve our ability to monitor, evaluate and engage with our own thoughts – so-called metacognitive ability.